1. Field of the Invention
The present invention relates to a plasma source, and more particularly, to an inductive coupled plasma source and an inductive plasma chamber comprising a plurality of discharge tube bridges.
2. Description of the Prior Art
Plasma is a highly ionized gas containing an identical number of positive ions and electrons. At the present time, plasma sources have a variety of applications in several fields. The plasma sources are being used for example for cleaning, etching, deposition, and the like in manufacturing semiconductor devices for producing semiconductor chips.
Generating technologies of inductive coupled plasma (ICP) or transformer coupled plasma (TCP) have been extensively studied in this application field. The RF ICP technology has the advantage that there is no electrode to be in contact with the plasma in providing electro-magnetic energy for generating the plasma. A capacitive coupled plasma (CCP) method using an electrode has a bad influence upon a final product because impurities are generated from the electrode in contact with plasma.
The generating technologies of the inductive coupled plasma (ICP) or the transformer coupled plasma (TCP) have extensively studied in this application field. Capacitive Coupled Plasma (CCP) method using the electrode has a bad influence upon the final product because impurities are generated from the electrode in contact with the plasma. However, a RF ICP method has an advantage of not having electrodes in contact with the plasma in providing electro-magnetic energy for plasma generation. As a technology related to an early ICP technology, a technology related to an inductively coupled discharge for plasma etching and resist stripping is disclosed in U.S. Pat. No. 4,431,898 issued Feb. 14, 1984 to Alan R. Reinberg et al.
Recently, a plasma source with larger volume, uniformity and high density is required as a workpiece becomes larger in the technical field using the plasma. In a case of a semiconductor device field, a plasma source capable of effectively processing a large-sized wafer is required, and a plasma source enabling the liquid crystal display panel having a large size to be processed is also required in production of the liquid crystal display panel. However, the ICP technology is difficult to obtain high-density plasma having high uniformity only by simply enlarging the size of an inductive coil or a transformer to obtain the plasma having a large volume.
As a related technology, an inductive RF plasma source with an external discharge bridge is disclosed in U.S. Pat. No. 6,392,351 issued on May 21, 2002 to Evgeny V. Shun'ko. An inductively coupled ring-plasma source apparatus for processing gases and materials and a method thereof is disclosed in U.S. Pat. No. 6,432,260 issued on Aug. 13, 2002 to Leonard J. Mahoney.
However, it is difficult to obtain high-density plasma with improved uniformity along with a large volume only with a C-shaped bridge to which a transformer proposed in the above-stated technologies is coupled. For example, a connection structure between the C-shaped bridge and a working chamber or a process chamber is a structure in which it is difficult for plasma gas to uniformly diffuse while maintaining a high density in the working chamber. Further, if the plasma source comprises a plurality of C-shaped bridges as in these technologies, a gas supply structure for supplying process gases is inevitably designed in a complex structure.